Shielded Conduit Protects Against EMI/RFI

Electri-Flex Co.

Electri-Flex Company manufactures a broad line of shielding conduits that are designed to protect sensitive electronic circuits from electromagnetic and radio frequency interference (EMI/RFI) in a variety of applications. These applications are found in aerospace, communications, radar and data transmission, and many other industries where commercial off the shelf (COTS) products are acceptable.

Markets and ApplicationsElectri-Flex’s shielded conduit can be used in a variety of markets and applications. Markets such as industrial, HVAC, and utilities – especially water and wastewater– use variable speed drives. Also called variable frequency drives, these devices are extremely susceptible to radio frequency interference. Using shielded flexible conduit from the drive controller to the motor eliminates the potential for hazardous interference in the operation of the drive. Flexible shielded conduit is also often used in building automation applications such as dampers, blower motors, and electronic controllers.

Flexible shielded conduit is very often used in data center wiring to keep power wiring from interfering with signal and data lines, and, for similar applications, in test and measurement. It is also used in transportation and aerospace applications, where space is at a premium and the flexibility is an advantage, such as in trains, subways, and both military and civilian aircraft.

The use of flexible shielded conduit is also superior to the use of shielded cable because the conduit’s construction protects from damage to the jacket and inner conductors of the cable. Product TypesThe three types of shielded conduit can be classified as "good," "better," and "best" solutions to provide effective shielding from RFI and EMI interference.

Good Shielding: Type SLA, UL Listed, is a flexible steel conduit with a galvanized steel core, over which a tinned copper shielding braid is applied. The outer jacket is flexible PVC with a temperature rating of -30° to 80°C Dry / 60°C Wet / 70°C Oil while the braid offers a minimum of 90% shielding coverage.

Better Shielding: Type EMS offers a better shielding effectiveness than Type SLA with a temperature rating of -55°C to 105°C. EMS features a flexible core constructed of a helically wound, fully interlocked strip of bronze. An all-temperature PVC jacket is extruded over the core, resulting in a sealed, waterproof raceway when assembled with liquidtight fittings.

BEST Shielding: Type EMCS is a hybrid of SLA and EMS because it utilizes the same bronze core and PVC jacket as EMS but gets further screening protection from a tinned copper braid as found in the SLA product. Type EMCS offers the same working temperatures as EMS.